Large stiffened composite panels are being used in new commercial aircraft. These panels include stiffeners co-bonded with composite webs and skin.
Co-bonding offers certain advantages over fastening stiffeners to webs and skin. Co-bonding can reduce or eliminate fastening operations (e.g., hole generation and fastener installation), thereby reducing complexity, weight, cost of materials, tooling costs, inventory, and manufacturing flow time
However, co-bonding can produce undesirable effects such as ply wrinkles, adhesive pockets, and resin pockets. These effects are typically formed at stiffener edges.
A need exists for a composite panel including stiffeners co-bonded with composite webs and skin, without having such undesirable effects.